The present invention relates to a DDS compound (DDS: drug delivery system) in which a carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound and a drug compound such as antineoplastic agents are bound to each other. The present invention also relates to a method for measurement of a DDS compound in which a polymer carrier and a drug compound such as antineoplastic agents are bound to each other.
Antineoplastic agents, used for treatment of solid cancers such as lung cancer or digestive organ carcinomas and blood cancers such as leukemia, are systemically administered through routes of administration such as intravenous or oral administration, and then, are distributed to certain tumorous sites and inhibit or suppress the proliferation of cancer cells to exhibit their therapeutic efficacy. However, the systemically-administered antineoplastic agents are rapidly taken into livers and reticuloendothelial organs from blood, or rapidly excreted into urine, and accordingly, their blood concentrations may be sometimes too low to distribute to tumorous sites sufficiently. In addition, common antineoplastic agents themselves do not distribute tumorous sites selectively (tumor selectivity), and therefore, the antineoplastic agents are uniformly distributed over various tissues and cells of the whole body and act as cytotoxins also against normal cells and tissues, which results in problems of the appearance of adverse effects, e.g., emesis, pyrexia, or alopecia at an extremely high rate. Therefore, it has been desired to develop a means of efficiently and selectively distributing antineoplastic agents to tumorous sites.
As one of such means, a process was proposed in which a polysaccharide derivative having carboxyl groups is used as a polymer carrier, and an antineoplastic agent is bound to the polymer carrier to delay the disappearance of the antineoplastic agent from blood and to enhance selectivity to tumor tissues. For example, International Publication WO94/19376 discloses a DDS compound in which a peptide chain (the number of amino acid residues: 1 to 8) is bound to a carboxyl group of a polysaccharide having carboxyl groups, and doxorubicin, daunorubicin, mitomycin C, bleomycin or the like is further bound by means of the peptide chain. In addition, Japanese Patent Publication (KOKOKU) No. (Hei) 7-84481/1995 discloses a DDS compound in which the aforementioned antineoplastic agent is introduced into a carboxymethylated mannoglucan derivative by means of a Schiff base or an acid amide bond.
These DDS compounds (also referred to as xe2x80x9cdrug complexesxe2x80x9d) are characterized in that they have more excellent antineoplastic activity, reduced toxicity and adverse effects compared to antineoplastic agents, per se, that are bound to polymer carriers. The inventors of the present invention have provided a DDS compound which is formed by binding a polymer carrier such as polysaccharide compounds to a drug compound such as antineoplastic agents by means of a spacer consisting of one to eight amino acids, and which can site-selectively distribute the drug compound such as antineoplastic agents to target tissues (International Publication WO97/46260). They have also found that a carboxy(C1-4)alkyldextran polyalcohol has highly desirable characteristics as a polymer carrier, and provided a DDS compound containing a carboxy(C1-4)alkyldextran polyalcohol as a polymer carrier (the above mentioned International Publication).
As for technologies relating to DDS compounds utilizing polyalcoholized polysaccharide derivatives as polymer carriers, some reports are available, for example, xe2x80x9cResearches on polysaccharide-peptide-doxorubicin complexesxe2x80x94Correlations between stabilities of polysaccharide carriers in blood and their anti-neoplastic activitiesxe2x80x9d (Abstracts of 10th Meeting of the Japan Society of Drug Delivery System, 279, 1994); xe2x80x9cResearches on polysaccharide-peptide-doxorubicin complexesxe2x80x94Pharmacokinetics and anti-neoplastic activityxe2x80x9d (Abstracts of 9th Annual Meeting of Japanese Society for the study of xenobiotics, 292, 1994); Abstracts of 19th Seminar of Trends in Research and Development (held by The Organization for Pharmaceutical Safety and Research), D-9, 1995; and xe2x80x9cResearches on drug delivery to a tumor tissue by polysaccharide carriersxe2x80x9d (Abstracts of 12th Colloid and Interface Technology Symposium, The Chemical Society of Japan, 51, 1995).
As means for enhancing organ selectivity of polysaccharide compounds and the like, for example, saccharide-modified polyglutamic acid derivatives (Japanese Patent Unexamined Publication (KOKAI) (Hei) No. 5-178986/1993), saccharide-modified polylysine derivatives (Japanese Patent Un-examined Publication (KOKAI) (Hei) No. 5-222187/1993), D-galactopyranosylgluconic acid derivatives of a poly-xcex5-substituted-L-lysine (Japanese Patent Unexamined Publication (KOKAI) (Hei) No. 7-70311/1996), saccharide-modified poly-xcfx89-substituted-L-glutamic acid derivatives (Japanese Patent Unexamined Publication (KOKAI) (Hei) No. 7-228688/1995), polysaccharide compounds bound to a saccharide compound by means of a linker (Japanese Patent Unexamined Publication (KOKAI) (Hei) No. 8-85703/1996), glucosyl-protein derivatives (Japanese Patent Un-examined Publication (KOKAI) (Hei) No. 9-118699/1997) and the like have been known. However, any techniques for enhancing organ selectivity of DDS compounds have not been reported so far in which a carboxy(C1-4)alkyldextran polyalcohol is used as a polymer carrier.
When a DDS compound is clinically used in which a polymer carrier and a residue of a drug compound are linked to each other by means of a spacer containing an oligopeptide, it is necessary to accurately measure a blood concentration of the DDS compound, per se, and also to accurately measure a content of the residue of the drug compound, such as antineoplastic agents introduced to the DDS compound, to determine an appropriate dosage or to test lot differences of products. The measurements of a blood concentration of a DDS compound and a content of residue of a drug compound in the DDS compound have conventionally been performed by measuring the DDS compound directly, per se, based on fluorescence of the drug compound or its UV absorption without cleaving the drug compound or the drug compound bound with a part of the spacer from the DDS compound. Furthermore, a method based on NMR analysis of a DDS compound, per se, and a method of measuring a decomposed product obtained by an acid treatment of a DDS compound have also been proposed.
However, those methods have problems in that a quantitative measurement of a decomposed product by an acid treatment cannot be performed when the drug compound is susceptible to an acid, and accuracy of the NMR analysis is insufficient. Moreover, UV absorption of a residue of a drug compound present in a DDS compound may cause a shift of maximum absorption wavelength or a change in molar extinction coefficient relative to the drug compound itself because of effects of a polymer carrier or a peptide spacer, and therefore, it is generally difficult to accurately measure a content of a residue of a drug compound introduced into a DDS compound. It is extremely difficult to quantitatively measure a DDS compound in tissues after administration to living bodies by the methods based on NMR analysis or UV absorption.
An object of the present invention is to provide a means for enhancing organ selectivity (e.g., selectivity to liver or the like) of DDS compounds containing a carboxy(C1-4)alkyldextran polyalcohol as a polymer carrier, and to provide a DDS compound having the aforementioned characteristics.
Another object of the present invention is to provide a polysaccharide compound useful as a raw material for the manufacture of DDS compounds having the aforementioned characteristics.
A still further object of the present invention is to provide a method for measuring a DDS compound in which a polymer carrier and a residue of a drug compound are bound to each other by means of a spacer that comprises an oligopeptide. More specifically, the object of the present invention is to provide a method for accurately measuring the DDS compound, per se, or a content of the residue of the drug compound such as antineoplastic agents introduced to the DDS compound. Further specifically, the object of the present invention is to provide a method for determining an acurate concentration of the DDS compound in blood or a tissue after administration, or a method for determining of a content of the residue of the drug compound introduced to the DDS compound accurately.
The inventors of the present invention earnestly conducted intensive studies to achieve the foregoing objects, and as a result, found that a DDS compound with extremely high organ selectivity was obtainable by using a carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound as a polymer carrier, and that a DDS compound containing the carboxy(C1-4)alkyldextran polyalcohol bound to galactose, in particular, had excellent liver selectivity.
Moreover, the inventors of the present invention also found that a blood concentration of a DDS compound or a content of residues of a drug compound introduced to the DDS compound can be accurately and easily determined by treating a DDS compound with a peptidase in which a polymer carrier and a residue of drug compound are bound to each other by means of a spacer containing an oligopeptide, and measuring a resulting hydrolysate. The present invention was achieved on the basis of these findings.
The present invention thus provides a DDS compound comprising a carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound and a residue of a drug compound bound to the carboxy(C1-4)alkyldextran polyalcohol.
According to preferred embodiments of the DDS compound, the present invention provides the above DDS compound wherein the carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound and the residue of a drug compound are bound to each other by means of a spacer; the above DDS compound wherein the spacer comprises one amino acid or 2 to 8 amino acids linked by peptide bond(s); the above DDS compound wherein the carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound is formed by binding a saccharide compound and a carboxy(C1-4)alkyldextran polyalcohol by means of a linker; and the above DDS compound wherein the carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound is a compound with cluster modification by a saccharide compound bound by means of a linker.
The present invention also provides a DDS compound which is obtainable by binding a residue of a drug compound to a carboxy(C1-4)alkyldextran polyalcohol in which a part of carboxyl groups of the carboxy(C1-4)alkyl moiety are modified with a saccharide compound.
According to preferred embodiments of the DDS compound, the present invention provides the above DDS compound which is obtainable by binding the carboxy(C1-4)alkyldextran polyalcohol and the residue of a drug compound by means of a spacer; and the above DDS compound which is obtainable by binding the residue of drug compound to the carboxy(C1-4)alkyldextran polyalcohol which is produced by binding the saccharide compound or a linker bound to the saccharide compound to a part of carboxyl groups of the carboxy(C1-4)alkyl moiety of the carboxy(C1-4)alkyldextran polyalcohol.
The present invention further provides a DDS compound which is obtainable by modifying, with a saccharide compound, a carboxy(C1-4)alkyldextran polyalcohol in which a residue of a drug compound is bound to a part of carboxyl groups of the carboxy(C1-4)alkyl moiety by means of a spacer.
According to preferred embodiments of the aforementioned DDS compound, the present invention provides the above DDS compound which is obtainable by binding the carboxy(C1-4)alkyldextran polyalcohol and the saccharide compound by means of a linker; and the above DDS compound which is obtainable by modifying, with a saccharide compound, a carboxy(C1-4)alkyldextran polyalcohol produced by binding a residue of a drug compound to a part of carboxyl groups of the carboxy(C1-4)alkyl moiety by means of a spacer comprising one amino acid or a spacer comprising 2 to 8 amino acids linked by peptide bond(s).
According to further preferred embodiment of the present invention, there are provided the above DDS compounds wherein the saccharide compound is galactose, galactosamine or derivatives thereof; the above DDS compounds wherein the dextran polyalcohol that constitutes the carboxy(C1-4)alkyldextran polyalcohol is a dextran polyalcohol which is obtained by treating a dextran under conditions that enable substantially complete polyalcoholization; the above DDS compounds wherein the carboxy(C1-4)alkyldextran polyalcohol is carboxymethyldextran polyalcohol; the above DDS compounds wherein substitution degree of galactose or galactosamine or a derivative thereof, or a that of a clustered galactose or galactosamine or a derivative thereof is 0.01 to 1.0 per saccharide residue of the carboxy(C1-4)alkyldextran polyalcohol; the above DDS compounds wherein the drug compound is an antineoplastic agent or an anti-inflammatory agent; the above DDS compounds wherein the drug compound is (1S,9S)-1-amino-9-ethyl-5-fluoro-2,3-dihydro-9-hydroxy-4-methyl-1H,12H-benzo[de]pyrano[3xe2x80x2,4xe2x80x2:6,7]indolizino[1,2-b]-quinoline-10,13(9H,15H)-dione; and the above DDS compounds which are a medicament for treating liver cancer.
According to other aspects of the present invention, there are provided a carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound; a polymer carrier comprising a carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound; and a carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound for a use in the manufacture of the above DDS compounds. According to further aspect of the present invention, there is provided a use of a carboxy(C1-4)alkyldextran polyalcohol modified with a saccharide compound for the manufacture of the above DDS compounds.
According to a still further aspect of the present invention, there is provided a method for measuring a DDS compound in which a polymer carrier and a residue of a drug compound are bound to each other by means of a spacer comprising 2 to 8 amino acids linked by peptide bond(s), which comprises the steps of treating the DDS compound with a peptidase, and measuring a resulting hydrolysate.
According to preferred embodiments of the aforementioned method, there are provided the above method which is used for measurement of the DDS compound contained in a sample from a living body; the above method which is used for measurement of content of the residue of a drug compounds introduced to the DDS compound; the above method wherein the hydrolysate is the drug compound; the above method wherein the hydrolysate is a compound consisting of the residue of a drug compound bound with a part of the spacer; and the above method wherein a part of the spacer is one amino acid derived from the spacer.
According to further preferred embodiments of the aforementioned method of the present invention, there are provided the above method wherein the polymer carrier is those is those having carboxyl groups, preferably a polysaccharide derivative having carboxyl groups; the above method wherein the polymer carrier is a carboxy(C1-4)alkyldextran polyalcohol, preferably carboxymethyldextran polyalcohol; the above method wherein the dextran polyalcohol that constitutes the carboxy(C1-4)alkydextran polyalcohol is a dextran polyalcohol which is obtained by treating a dextran under conditions that enable substantially complete polyalcoholization; the above method wherein the polymer carrier is modified with a saccharide compound; the above method wherein the drug compound introduced to the DDS compound is an antineoplastic agent or an anti-inflammatory agent; the above method wherein the spacer is a tetrapeptide represented as, from the N-terminal, -Gly-Gly-Phe-Gly- (SEQ ID NO. 1) or a tetrapeptide represented as, from the N-terminal, -Gly-Gly-Gly-Phe- (SEQ ID NO. 8); the above method wherein the spacer is a group represented as, from the N-terminal, -Gly-Gly-Phe-Gly-NHxe2x80x94Yxe2x80x2xe2x80x94CH2xe2x80x94Oxe2x80x94COxe2x80x94 (SEQ ID NO. 1) or -Gly-Gly-Gly-Phe-NHxe2x80x94Yxe2x80x2xe2x80x94CH2xe2x80x94Oxe2x80x94COxe2x80x94 (SEQ ID NO. 8) wherein Yxe2x80x2 represents p-phenylene group; the above method wherein the peptidase is xcex1-chymotripsin or papain; and the above method wherein the drug compound is (1S,9S)-1-amino-9-ethyl-5-fluoro-2,3-dihydro-9-hydroxy-4-methyl-1H,12H-benzo[de]pyrano[3xe2x80x2,4xe2x80x2:6,7]indolizino[1,2-b]quinoline-10,13(9H,15H)-dione.
According to a particularly preferred embodiment of the above method of the present invention, the above method can be used for measurement of a DDS compound in which a carboxy(C1-4)alkyldextran polyalcohol and (1S,9S)-1-amino-9-ethyl-5-fluoro-2,3-dihydro-9-hydroxy-4-methyl-1H,12H-benzo[de]pyrano[3xe2x80x2,4xe2x80x2:6,7]indolizino[1,2-b]quinoline-10,13(9H,15H)-dione are bound to each other by means of a spacer comprising a tetrapeptide represented as, from the N-terminal, -Gly-Gly-Phe-Gly- (SEQ ID NO. 1) or a tetrapeptide represented as, from the N-terminal, -Gly-Gly-Gly-Phe- (SEQ ID NO. 8), and the DDS compound or a content of the antineoplastic agent introduced to the DDS compound can be measured by using xcex1-chymotrypsin as the peptidase, and by measuring (1S,9S)-9-ethyl-5-fluoro-1-glycylamino-2,3-dihydro-9-hydroxy-4-methyl-1H,12H-benzo[de]pyrano[3xe2x80x2,4xe2x80x2:6,7]indolizino[1,2-b]quinoline-10,13(9H,15H)-dione as the hydrolysate.